This invention relates to meat tenderizers with a force-limited apparatus for tenderizing meat. More particularly, the invention relates to a meat tenderizer with a non-magnetic force-limited apparatus for tenderizing meat that utilizes a series of coated bars and a set of orthogonal blades, which is an improvement over known apparatuses.
In the art of mechanically tenderizing meat, it is known that to tenderize a piece of tough meat a meat tenderizing apparatus typically stabs or cuts the meat with a plurality of sharp blades as is shown in U.S. Pat. No. 4,169,300 to McCullough, and herein incorporated by reference. In addition, McCullough teaches that to protect the blades from damage when encountering bone in the meat a mechanism of springs and ball bearings can be used to allow any blade to be released if bone or other hard matter is encountered. However, McCullough""s device requires numerous small parts and is difficult and expensive to assemble and maintain.
In U.S. Pat. No. 4,437,207 to Ross, a plurality of cobalt-sumarian alloy magnets that magnetically couple with blade xe2x80x9cpolesxe2x80x9d made from special silicon iron alloys are used. Ross thus provides an alternate mechanism for achieving the same result; that is, to allow any blade to be released when bone or other hard matter is encountered by the blades. However, the magnets disclosed by Ross are expensive and many are needed to make the device. Furthermore, the magnetic mechanism is not durable because the xe2x80x9cpolesxe2x80x9d attached to the blades and made of the special silicon iron alloy corrode and fail to effectively couple with the magnets. In addition, meat tenderizing blades often wear out or arc damaged under normal operating conditions and need to be replaced. It is expensive to replace the blades required by the Ross patent because of the pole made of a costly alloy.
However, the present inventor has found that the most cost efficient mechanical meat tenderizer is disclosed in U.S. Pat. No. 6,120,368 to Ter-Minassian, the entire disclosure of which is incorporated herein by reference. The meat tenderizer disclosed by Ter-Minassian has a force limited apparatus for protecting the blades comprising a friction plate manufactured with a plurality of square holes for frictionally engaging a plurality of meat cutting blades. Each square hole frictionally engages one blade, and each blade is made with a frictional portion for engaging two opposing walls of a corresponding square hole. The frictional portion of each blade is a spring formed as part of the blade.
The Ter-Minassian meat tenderizer has the advantages that it is practical and cost effective to manufacture, durable, easy to clean and easy to maintain; however, the device has several problems. First, to make the square holes in the friction plate, it is most cost efficient to use a punch. Other technologies can be used, such as lasers or high velocity water drills, but these methods are expensive. The drawback of using a punch to make the square holes is that the holes are less uniform. Small variations in the geometry of the hole on the order of a thousandth of an inch can have dramatic consequences. Specifically, it has been found that the ideal release force on each blade is about 4 pounds. At this force, each blade can perform its cutting function optimally with minimal risk of damage to the blade. When the Ter-Minassian friction plate is made using a punch to form the square holes, the force required to frictionally disengage the springs of the blades from the square holes averages about 4 pounds, but the variance is +/xe2x88x922 pounds. Consequently, some of the blades are prone to damage when not released at 4 pounds of force and other blades are released prematurely and fail to perform an adequate cut.
In addition, once a blade has been released by the force-limiting apparatus, a plate is used to reset all of the released blades back into each respective square hole before further cuts can be made into the meat to be tenderized. To perform its optimal tenderizing function, each Ter-Minassian meat tenderizer utilizes hundreds of blades; therefore, over a thousand pounds of force may been needed to reset the blades. This great amount of force required for reset is another drawback of the Ter-Minassian meat tenderizer.
The present invention endeavors to provide an improved mechanical meat tenderizer with a force limited apparatus for protecting the blades that maintains the advantages of the Ter-Minassian device while overcoming the drawbacks of the prior art machines.
Accordingly, a primary object of the present invention is to overcome the disadvantages of the prior art mechanical meat tenderizers.
Another object of the present invention is to provide a mechanical meat tenderizer with an improved force limiting apparatus that is practical and cost effective to manufacture.
Another object of the present invention is to provide a mechanical meat tenderizer that is both durable and reliable.
Another object of the present invention is to provide a mechanical meat tenderizer that is both easy to clean and easy to maintain.
Another object of the invention is to provide a mechanical meat tenderizer that achieves a substantially uniform release force for every blade of a plurality of blades.
Another object of the invention is to provide a mechanical meat tenderizer that has a plurality of blades that reset by applying a minimal force.
Another object of the invention is to provide a mechanical meat tenderizer that functions using blades that are easy and inexpensive to replace.
In accordance with the above objectives, the present invention provides an apparatus for mechanically tenderizing meat comprising (1) a plurality of elongated cutting blades having cutting edges formed on one end thereof, a frictional member proximate another end thereof, and a longitudinal axis; and
(2) a reciprocatable head holding the plurality of cutting blades and movable from a first position wherein the plurality of blades is retracted to a second position wherein the plurality of blades is extended. The reciprocatable head comprises (a) a meat securing member, (b) a friction plate, and (c) a blade orienting member disposed to orient the blades in spaced relationship so that the longitudinal axis of each blade is aligned substantially parallel to the longitudinal axis of each other blade. The friction plate further comprises a plurality of friction bars disposed to frictionally engage the friction members of the blades, wherein each bar of the plurality of bars frictionally engages the frictional member of each blade of a respective set of the blades so that a predetermined force is provided for independently holding each of the blades in a fixed position with respect to the friction plate as the blades move to the second position.
The desired objectives are also achieved by one embodiment of the mechanical meat tenderizer of the present invention by employing an improved force-limiting apparatus and sets of orthogonal blades. The force limiting apparatus comprises a friction plate comprising a frame plate having an upper face and a lower face, with a plurality of longitudinal grooves formed on the lower face wherein the plurality of longitudinal grooves comprise two lateral grooves and at least one center groove so that a longitudinal ridge is disposed between every two longitudinal grooves; and, a plurality of blade holes formed in the frame plate wherein each blade hole opens onto the upper face and the lower face and is centered on a corresponding longitudinal ridge so that each blade hole is bordered by at least one island formed from a portion of the corresponding longitudinal ridge, and so that each blade hole has a portion formed in two adjacent grooves of the plurality of longitudinal grooves. Furthermore, the friction plate comprises a plurality of bars disposed respectively in the plurality of longitudinal grooves, wherein each bar encroaches upon and narrows a corresponding number of respective blade holes so that two adjacent bars provide corresponding two square faces for frictionally engaging a spring of a cutting blade that is disposed within a corresponding blade hole.
In a preferred embodiment, each bar is coated with a hard, low friction finish, such as CASIDIAM(trademark).
In another preferred embodiment, the friction plate further comprises a face plate comprising a outer face and an inner face, and a plurality of holes formed in the face plate, wherein each hole opens on the outer face and the inner face and so that each hole corresponds to a respective blade hole of the frame plate.
In another preferred embodiment, the set of orthogonal blades comprises a plurality of orthogonal blade pairs disposed in the plurality of blade holes, wherein each orthogonal blade pair includes a first blade and an orthogonal second blade, wherein each first blade is disposed on the frame plate to be adjacent to a corresponding orthogonal second blade.
In yet another embodiment, the present invention provides a method for tenderizing meat. The method comprises the step of (1) providing an apparatus comprising: (a) a plurality of elongated cutting blades having cutting edges formed on one end thereof, a frictional member proximate another end thereof, and a longitudinal axis; and (b) a reciprocatable head holding the plurality of cutting blades and movable from a first position wherein the plurality of blades is retracted to a second position wherein the plurality of blades is extended. The reciprocatable head comprises (i) a meat securing member, (ii) a friction plate, and (iii) a blade orienting member disposed to orient the blades in spaced relationship so that the longitudinal axis of each blade is aligned substantially parallel to the longitudinal axis of each other blade. The friction plate comprises a plurality of friction bars disposed to frictionally engage the friction members of the blades, wherein each bar of the plurality of bars frictionally engages the frictional member of each blade of a respective set of the blades so that a predetermined force is provided for independently holding each of the blades in a fixed position with respect to the friction plate as the blades move to the second position. The method further comprises the steps of (2) holding meat with the meat securing member; and (3) reciprocating the reciprocatable head from the first position to the second position to mechanically tenderize the meat.
In a still further embodiment, the reciprocating step includes releasing any blade of the set of orthogonal blades that encounters a release force exceeding the predetermined force for holding each of the blades in a fixed position.
In another embodiment, the method further comprises, the steps of returning the head and the blades to the first position; resetting any released blades using a press plate; and repeating the reciprocating step.